Multiple stage carburetor



MULTIPLE STAGE CARBURETOR Filed Deo. 8, 1955 6 Sheets-Sheet l 6Sheets-Sheet 2 Filed Dec. 8, 1953 INVENTOR. Jrn/4 d, Sarita Nov. 1, 1955J. o. SARTO 2,722,207

MULTIPLE STAGE CARBURETOR Filed Dec. 8, 1953 6 Sheets-Sheet 5 I N V ENTOR. J2 f77/4 $47214 Z BY fr fa )wwf/g Nov. 1, y1955 J. o. sAR'roMULTIPLE STAGE CARBURETOR Filed Dec. 8, 1953 e sheets-sheet 4 f Y l )Ahhl 7&5#

IN V EN TOR.

72777774 Saffo MMM Nov. l, 1955 J. o. sARTo 2,722,207

MULTIPLE STAGE CARBURETOR Filed Dec. 8, 1953 6 Sheets-Sheet 5 INVENTOR.L75 77774 Se 7'210 MMM Nov. l, 1955 J. o. sARTO MULTIPLE STAGECARBURETOR 6 Sheets-Sheet 6 Filed Dec. 8, 1953 MM MM 4/.e/c# 4 4 M a l 4w f o i M M 5 m1@ l M f m5 A y 0. el l m 2 w ,w www JW f. j/V/7 M f f yM @Z y@ i j United States Patent() MULTIPLE .STAGE cARBURET-.OR

ApplicatiomDecemberzS, 19153, Serial No..396,^9.82

3S Claims. .(Cl. '12S-#127.)

This kinvention :relates to multiple stage liquid fuel carburetors forinternal combustion engines and :more particularly toa means for.controlling the .actuation of an auxiliary carburetor stage -of amultiple stage carburetorin response to engine speed. f

The characteristics of a conventional internal' .comibustion engineequipped with a .liquid Afuel carburetor .are such that the :engineoutput .torque will kvary with -a lvariation in engine speed. 'Thisvariation .in .engine torqueis caused by a `numberof factors, one of.which is the change in the fuel vmixing characteristics .of the carafburetor which accompanies "a variation `in v:engine speed rdesign. .Asthe engine `speed increases,:the;intake airiflow rate within theycarburetor fuel .fmixing throat is also increased. When ya lsinglestage .carburetor zisaused, the air dl'ow .rate *which would produceSthe .optimum fuel mixing .characteristics .in .the :single mixingthroat tthereof willrnor- :mally occur throughout .a low engine .speedrange. .At .arelatively .higher feng'ine speed range the :mixing char-.acteristics :and air .fuel ratio may :deviate from :the I.optimum .andfor this reason the engine .output torque will normally .tend to.decreasew'ith an'increase in engine fspeed.

tlf a dual barrel carburetor iis employed, `and Tiif :both ofthe 'mixingthroats are operative :over .the entire engine speedrange the air tlow-rate l,which would teXist Iin veach :of the `.throats 4at .low enginespeeds "would '.'be 5such athat the mixing characteristics would :be.relatively rpoor. On the yother jhand, the :correct .iow .rate mayexist .at the higher lengine rspeeds. .'lhus, :.the engine :outputitorque will .tend'to'increa'se withan increase :in the .engine speed.throughout Aa substantial fportion zof 'the noverall Lspeed range belowthe `output :torque ibegins ;to Afall ofI or ;d e

crease.

Accordingly, .it has been foundrdesrableito render xthe secondaryl'stage -of a dual :carburetor zinstallation :inoperative lat the' lowerengine fspeeds and nto :render -the Vsame operative .at1hgherfenginespeeds. ,The dual :carburetor unit will, therefore, function -asasinglerstagercarburetor over the lower engine speed range ;and thesecondary ystage :thereof will funct-ionzonly. at .the highery engine:speed range thusmaking it possible toftake .advantage of 1the resultingoptimum mixing characteristics-forrboth stages .toobtain a lmaximumVenginepoutput torque -over ,the entire speed-range.

It .is desirable to provide .an automatic :meansl ifor controlling thesecondary ,stage .to-.causezthe :same :to '.be ac- Vtuated/at .fthefproper engine '-speed. vzlnrorder-to :avoid a sudden change :in ,the.magnitude :of the output torque, :it is :necessary tto `actuate ,fthesecondarystage fat anengine speed 'suchthat the engine output torque:during engine operation with only thel primary stagewillbesubstantially the same as :the .engine .output itorque ;during=operationwith -bothscarburetory stages.

-lnorder .that the controlmeans for :the secondary stage .mightbeactuated at the,proper-engine'speed,;itfis necessary .to ,obtain anengine speed signal .tofinitiate .the automatic controlresponse .In thepresentembodment ,such a speed signal may consist of the engine coolantpump 'Cil Aice

discharge :pressure Awhich in turn is proportional .to engine *speed.since tthe coolant pump is normally lpowered Adirectly lbyfthefengine.e

.A :primary .object .of the present invention is to provide ra meanswhich is `responsiveto .engine speed for-control.- ling .fthe .operationof the .second stage -of a'two-stagecar- :buretor 'so A.that the second:stage will be inoperative at `low'engine vspeeds .and operative at'higherengine speeds.

A more specic :object of the present :invention is to provide :a meanswhich is responsive to engine coolant .pump pressure to automaticallycontrol thesecond stage .of atwo-stage carburetor whereby the second:stage thereof :is rendered `operative fat speeds above .alpredetermined 'maximum .value :and at a predetermined y.range :ofthrottle positions.

`Another .object of the present invention .is 'to .provide an .automatic:control rfor -a multiple stage 4carburetor fac- Acoi-.ding .to .theprecedingtobjects wherein a means is pro- `.vided .for connecting 'thethrottle valves of the secondary .stage with-the .throttle .valves in,the primary stage during movement .tof the aprimary .throttle Valvethroughout -a range :of zpos'itions mear the wide lopen vthrottleposition. The primary throttle valve may 1in .turn be :actuatedmanually. i

.Another :object :of :the present invention is to Lprovide .an:automatic :control :for a Amultiple stage carburetor iaccording to thepreceding object wherein an engine speed :responsive device :associatedlwith ythe automatic -control -is fadapted to :adjust ythe :position Iofthe secondary :throttle valve actuating linkage at engine speeds above-a prede- :termined :value 'to :permit the linkage to befcontacted by .a.corresponding linkage `for the primary lthrottle vValve duri-ngmovement fof lthe primary throttle :valve through- :out faipredetermined vrange of positions thereby 'providing :for `anadjustment ofthe lfuel-air ratio over the throttle yspeed-.range` offfthe ysecondary stage.

Another .object .of the 4.present invention Vis to provide an automaticcontrol means according to .the Lpreceding yobject wherein the speedresponsive device comprises an .engine coolant pumppressure responsiveactuator-anda ".snap Y:type :valve :interposed in va -uid conduit'between -the :pressure .responsive actuator and the engine'coolantpump, the said snap type valve being'e'lectiveto cause 'the actuator.tobe positively and ifully actuatedisubstantially Ainstantaneously`when the pump pressure reaches a predetermined value.

Another io'bject of the Kpresent `invention is Vto provide anautomaticxcontrolfor a multiple stage carburetorwhich :is responsive'toengine speed and which comprises `an Vengine Aspeed @responsive actuatorpositively A connected to 'an auxiliary stage=valve.

Another object of the present yinvention is `to provide fan automatic:control fas set forth in the `preceding object fwhereinthe.engine.speed signal for the speed responsive actuator is obtainedfrom the engine coolant pump ypres- :sure .and :wherein .a :fluidconduit -is rprovided between the actuator and the engine coolant pump.Auid control fvalve l'is interposed 'in the conduit and actuated by'meansof theprimaryy throttle assembly.

In :.general, the `present invention as herein disclosed, comprisesaVcarburetor having a'pair of primary fueljmix yingrbarrelsvand a pairo'fauxiliary'barrels which Vare "associated with the primary andsecondary stages respectively. Each of vvthe barrels is provided with athrottlelvalve :for .controlling rthe intake :air lflow ratestherethrough. The throttle valves :for-.theprimary stage are mounted fintandem -upon ,a ,common shaft and the throttle valves forlthe.secondary-stage :are also mounted .in tandem 4upon another commonshaft. The lprimary vthrottle -shaft is positively linked to a .manuallyactuated -foot throttle lever and another portion of the,primary'throttlefshaft carries a lost motion element which is adapted tocontact J a mating lost motion element pivotally carried by a leverwhich in turn is connected to the secondary throttle shaft.

A coolant pump pressure responsive actuator is mounted upon thecarburetor and is linked to the pivoted lost motion element. Uponreaching a predetermined value the coolant pump pressure causes theactuator `to move its associated lost motion element into `a position inthe path of movement of the other lost motion element as the primarythrottle valve moves toward the wide open position. Therefore, theprimary throttle valve linkage is adapted to control the opening of thesecondary throttle during movement of the primary throttle valvethroughout a predetermined operating range and when the speed of theengine exceeds a predetermined minimum value.

According to another embodiment of the invention a coolant pump pressureresponsive actuator is provided on a four-barrel carburetor and themovable element of the actuator is positively linked to the secondarythrottle shaft to actuate the same when the speed of the engine reachesa predetermined minimum. No direct mechanical connection is providedbetween the primary and secondary valves in this embodiment. However,the movement of the primary valve is effective to control the movementof a control valve which regulates the delivery of coolant pressure fromthe coolant pump to the actuator.

For the purpose of more particularly describing the present invention,reference will be made to the accompanying drawings in which:

Figure 1 is a top view of a four-barrel carburetor equipped with thesecond stage control of the present invention;

Figure 2 is a side view of the carburetor of Figure 1 showing a portionof the linkage associated with the primary and secondary stages;

Figure 3 is a bottom view of the carburetor of Figure 1;

Figure 4 is a side view of the carburetor of Figure 1 showing the sideopposite from that shown in Figure 2;

Figures 5, 6, and 7 are perspective views of the throttle valves and theassociated control levers. Each of the views shows the levers inrelatively different positions for the purpose of more clearlyillustrating the operation of the invention;

Figures 8 and 9 schematically show a modified arrangement of the controllevers for the throttle valves. The coolant pump pressure responsiveactuator is shown in the deenergized position in Figure 8 and in theenergized position in Figure 9;

Figure l is a schematic showing of another embodiment of the presentinvention which is similar to the ernbodiment of Figures 1 through 7;

Figure ll is a schematic representation of still another embodiment ofthe invention in which the coolant pump pressure responsive actuator isdirectly coupled to the secondary throttle shaft to actuate the same andin which the fluid conduit leading to the actuator includes a quickaction flow control valve;

Figure l2 is an alternative form of a flow control valve which may beused with any of the presently disclosed embodiments; and

Figure 13 is another modified form of the invention having a flowcontrol valve of a third form.

Referring first to the plan view of Figure l, the construction isdesignated generally by numeral 10 and, it includes four barrels whichare separately identified by means of numerals 12, 14, 16, and 18. Thefour barrels are divided into pairs of two by a vertical transverselyextending wall 70 which forms an integral part of the carburetor uppercast structure 22. The barrels 12 and 14 are grouped together on oneside of wall 70 and the barrels 16 and 18 are grouped into separatepairs on the opposite side of wall 20. It will be seen from thefollowing description that the pair of barrels 12 and 14 are associatedwith the primary stage and the pair of barrels 16 and 18 are associatedwith the secondary stage.

An automatic choke is shown generally at 24 and iS adapted to receiveexhaust manifold air through the fitting 26. A shaft 28 extends from thechoke device 24 through a suitable mounting portion 30 on the casting 22into the space above the barrels 12 and 14 and is adapted to berotatably adjusted by the choke device 24. A choke valve 32 is securedto the shaft 8 and is adapted to provide a choking action when the shaft28 is rotated. The choke valve 32 is shown in the fully open position inFigure l. The shaft 28 has an extension shown at 34 which carrieslinkage elements for causing shaft 28 to move a slight amount when theprimary throttle valve reaches the wide open position.

The presently disclosed carburetor also includes metering jets and anaccelerator pump boosting mechanism which are housed in a portion of thecasting 22 shown at 36. Suitable linkage elements are provided forpositively connecting thhe throttle linkage mechanism with a shaft 38which is rotatably mounted in a portion 40 of the casting 22 and whichis effective to control the elements within the casting portion 36.

A fuel inlet fitting is seen at 42 through which liquid fuel is admittedto a fuel bowl, not shown.

A venturi element is centrally disposed individually in each of thecarburetor barrels and are designated by numerals 44, 46, 48, and 50.Each of the venturis has a fuel jet disposed therein, as seen at 52, 54,56, and S8 respectively which are each adapted to discharge liquid fuelinto the intake air stream which flows through the barrels duringoperation of the engine.

In the bottom view of Figure 3 the throttle valves are clearly showndisposed in the downdraft end of the barrels 12, 14, 16 and 18 and areseparately designated by means of numerals 60, 62, 64, and 66,respectively. The downdraft portions of the four barrels are formed in asecond carburetor cast housing structure generally designated by numeralS9. The casting 59 is secured to the upper casting 22 previouslydescribed.

The pair of valves 60 and 62, which are secured to a primary throttleshaft 68, comprise the primary throttle valves and the remaining valves64 and 66, which are secured to a secondary throttle shaft 70, comprisethe secondary throttle valves. A suitable linkage element 72, whichforms a part of the throttle linkage mechanism, is positively connectedto the primary throttle valve shaft 68 in a suitable manner.

AReferring next to the side view of Figure 4, the linkage element 72 andthe associated linkage elements are shown in more particular detail. Theelement 22 has formed thereon suitable eyelets 74 which are adapted toreceive portions of a suitable manually actuated throttle linkagemechanism. The element 72 is also linked to a lever 76 by means oflinkage element 78 thereby causing the shaft38, upon which lever 76 issecured, to move in response to primary throttle movement. The movementof shaft 38 is effective to control the metering jets and theaccelerator pumping mechanism housed within casting portion 36.

Link elements 80 and 82 operatively connect the choke valve shaft 28with another link element 84 which is rotatably mounted upon a portionof the casting portion 59. A lost motion connection is provided at 86between the element 84 and another element 88 which is mountedconcentrically with respect to element 84 and which is also rotatableabout the common axis.

An abutment element is provided at on the primary throttle linkageelement 72 and is adapted to contact the element 88 when'the primarythrottle shaft 68 and the integral element 72 are rotated to a positionwhich is close to the full throttle position. Upon further movement ofthe element 72 toward the full or wide open throttle position, theelement 88 will be caused to rotate which in turn causes the element 84to rotate in the same direction by virtue of the lost motion connection84. If at this time the choke valve 32 is closed, the movement ofelement 84 will cause the links 82 and 8( l apre-'aow to move the chokevalve to a partially open position. lIf the choke valve has been openedby the thermostatic device 24, the slack in the iost motion connection86 is increased and therefore any movement of element 88 'by element 72will have no effect upon the .position 'of Jelement 84.

The element 88 is also provided with a cam surface 92 which is adaptedto be contacted by an adjustable stop 'device 94 carried by the element72. When the c'hok'e valve 32 lis in the closed position, the cam 92 andstop 94 prevent the primary throttle from fully closing. Also, if theprimary throttle is fully `closed v-when 'the choke valve 32 is open,the cam 92 and stop 94 'are effective to prevent the choke valve fromsubseyquent'ly moving to the fully closed position.

Referring'next to the side lview of Figure 2, it is vseen "thata'bracket y:96 is secured by means of screws 98 to a flange portionl*100 of the vupper casting portion 22. AThe bracket i96 has la 'mainportion thereof disposed in La substantially'vertical plane alongside4the lower casting 'portion 59.

'Theend portion of bracket 96 is `bent at a right angle fto the-1mainportion l96 and is shown at 100. A pressure responsive actuator device102, which is shown Lp'a'rt'lfyincross vsection in Figure 2, is securedto the end l-bracket portion 100 -by means of a suitable Athreaded1adaptor and nut 104.

`The -device 102 includes a housing 1506 which may include one ore more"flexible 'diaphragms 1508 which 'extend xtransversely across theinterior -of l'the "casting T06. The peripheral -portion oft'he'diaph'rag'm L108 may 'fb'e secured between the axial ends of thehousing '106 fand suitable en'd caps -110 'and 112. "If a -double dia-'-p'lira'grn actuator is used, as yin -theI disclosed "embodiment, `asuitable partition wall -114 may be provided -to separate the diaphragmsinto a pair of working chambers.

-An --actuator shaft 116 maybe slidably received Vwithin 'the end cap110 and the partition wall 108 vand secured to the 'central portion ofeach diaphragm 108. The shaft E11`1-"6-extenrls transverselythrough-thebracket portion 100 "and the adaptor andnut 104 in -parallelrelationship with v1respect to-the bracket portion 96. The 'end'of shaft1`16I-'carri`es va shoulder member v113 which may besli'dra'lilyldisposed around the shaft '116 adjacent a -nut A120 whichis threadably carriedby the end*of shaft116.

Aspring 119 surrounds shafts -1'16 and is interposed 'lbetweentheshoulder 118 and the nut 104 thereby urging vthe shaft 116 in an outwarddirection away lfrorn vthe 'device `102.

Allink element 122 is adapted to interconnect-thefend -of-lshaft 1:16and one arm ofaibell crank 124which is pivotally mounted to the bracketportion 96. nThe other arm ofthe'bellrcrank 124 is linked toacontrol-element 31256`by1means fof .the link element 128.

.Anabu'tment portion 130 is carried by the element V126 -attoneside ofthe connection between elements l12S and 126. A control element 132 Lisrotatably connected to th'ef'element i126 -at l134 on the other sideofthe 'abovemention'ed connection between felements 128 and y1-26. VT hecontrol element 132 is xed to one end ofthe secondary throttle shaft 70which extends through `the side -of=the lower casting portion 59.

VThe primary throttle shaft 68, which also fextends lthrough .the "sideof the 'casting portion S9, carries an arm 136 which carries anabutmentmember 138 at one lendlthereof The member 138 is pivoted to theend of -arm 1'36 upon a suitable fastener 140 and is'urged toward Va.xedpositionrelative to the arm 136 by means of an -otset 'spring means142.

,A .stop v144 `may be formed on the lower casting por- `tion v59 tocontact a mating shoulder 146 formed on the :element 132 whenthesecondary throttle reaches the fully .elosed'positionl AA suitable"spring means maybe pro- 6 nis not v"functioning to `regulate the.auxiliary .stage of the carburetor. A portion of such a spring means.may "be v.seeninFigurelZ'at148. v

The pressure responsive `actuator device .102 .may vbe 'provided with.suitable conduits 150 'and '1'52 which may be connected `to thedischarge side and the intake side, respectively, of 'the .coolant ,pump'for 'the internal lcombustion engine with which 'the present carburetoris adapted 'to ibe used. A quick action control valve,`whith willsubsequently be described with reference to the other embodiments of thepresent invention, may 'be interposed in `the 'iluid 4conduitsinterconnecting the .device 'I0-2 and "the engine coolant pump.

The operation of the embodiment of Figures 1 .through 4 may best bedescribed with reference to the perspective views of 'the throttle`valve control .elements shown in 'Figures 5, 6, .and '7. 4During `lowspeed operation of 'the engine, the engine coolant pump `pressure.,which is,p1'-o 'portion'al "to engine speed, 'acts against one of '.thediaphragms 108 through the conduit 15.0 but the force .exerted upon 'thediaphragm `-10`8 by the coolant ,pressure is in'sucient at 'the lower-eng'in'e speed ranges to overcome the 'force exerted vby spring v119.Thus the` shaft 11'6 remains 'stationary inthe .position shownin Figure5.

Upon movement of 'the .primary throttle toward the open position through.a manually actuated throttledikage, the arm 136 is adapted to rotatewith 'the.primary throttle shaft Ifrom the `position shown in "Figure 2to `that shown in Figure "5. When the wide openposition A-is reached.ifor the ,primary throttle, the arm and Vthe member 138 assume theposition shown inFigure'S which shows the member 138 in close,.proximityto .thefa'bub ment portion 130. 'The secondary throttle'valves .are maintained ina close'dposition throughout this low speedoperation.

l'During 'operation of 'the engine throughout a higher speed range,'th'eengine coolant pressure may increase 'to asu'icien'tly high `value tocause Ythe Vdiaphragms 108 `to `move 'the shaft '116 axially against'the force exerted A"by the spring 119. This 'movement of the shaft'11'6 causes 'the "bell 'crank'to rotate 'about its pivot point'thus'.causing the element "126 -to rotate about the connection .134

' 'to' an upward positionas shown'inFigure.4

-videdforrresiliently urging the shoulder 146 against the stop 144 tokeep the secondary throttle closed when it When the primary throttlevalves are moved toward r the Iwide open position 'during thisfhighspeed engine operation `the member '138 will contact 'the 'abutment 13.01beforeithefully openprimary throttle position .is reached. `-Uponfurther 'movement of .the .primary .throttle 'toward lthe 'wide openposition 'the arm 136 and member 138 willlthencause the element `176 torotate about ,itspivotal connection 'withthe link '128thuscausing theconnection 134 at theotherend of "element 126'to move in an up- `warddirection. This upwardlmovemen't causes thesecondary throttle valve toopenby virtue of the connecting lelement '132.

The lvalves andvalve control elements, as seen`in Fig `ure 6, are shownin the positions each assumes at lthe instant that the'member 138contacts the abutment 130. 'The shaft V11'6 is yshown in 'theoperativeposition it as- -sumes when the pressure responsive device 102is energized. The spring 119 is shown in the compressed posi- :tion--and the element 126 v:is vrotated about the connecltion i134 whichcauses the fulcrum point .for 'the element, `namel-y,the-'connectionwith link`128, to be shiftedin 'an upward direction.

f'Upon continued'movement of'the vprimary throttle .to 4'the fullthrottle position while the device 102 is thus fenergizellfthevalves andcontrol leverseach assume the `position shown in Figure/7. The arm 136and member 1`^3`8|cause the element 1'2'6`to-rotate about its connection'with liri'k 5128 which causes the secondary vvalves .60 an'd'62tto'cpen- Referring 'next 'to Figures *8 and 9, `a modified 'linkagearrangement' is jillustrated schematically. `The primary 'throttle'barrelis shown at 202 and the secondarybarrel is shown at 204. Aprimary valve 206 is rotatably disposed within the primary barrel 202and a secondary valve 208 is similarly disposed in barrel 204. Theprimary throttle valve 206 may be actuated by means of a suitablelinkage such as that shown at 210, 212, 214, 216, and 218. The component218 of the linkage may be manually actuated in the usual manner.

. The linkage component 210 is linked to a lever 220 by element 222which is joined to lever 220 at a substantially central position. Thelever 220 is connected at 224 at one end thereof to shaft 116 of thedevice 102 previously described in connection with the embodiment ofFigures 1 through 7. The free end 226 of the lever 220 is adapted toswing in an arc which is included by the angle 0.

The secondary throttle valve 208 is secured to a linkage element 228which is biased in a valve closing direction by a spring 230. Aprojection 229 is fixed to the element 228 in the path of movement ofthe end 226 of lever 220.

The engine coolant pump is shown schematically at 232 and a highpressure pump discharge conduit is shown at 234. The conduit 234 extendsto a quick action control valve 236 which comprises a two-part housing238 having an interior cavity 240 within which a ball 242 is adapted tofreely move. The ball 242 may be formed of steel or any other suitablematerial.

Another fluid conduit 244 is connected to one end of the valve housing238 and extends to the end cap 112 of the device 102 thus establishingfluid communication between the valve interior 240 and a working chamberwithin one portion of the device 102. A branch conduit 246 is effectiveto establish communication between conduit 244 and the low pressureintake side of the pump 232.

The conduits 234 and 244 are connected to the valve housing 238 atopposite ends thereof in coaxial alignment. Another conduit 248 isconnected with the housing 238 at a point intermediate the connectionswith conduits 234 and 244. Conduit 248 extends to the end cap 110 of thedevice 112 thus establishing fluid communication between the interior240 of valve housing 238 and another working chamber within anotherportion of the device 102.

The operation of the embodiment of Figures 8 and 9 of the linkagecomponent 210 which in turn causes the P lever 220 to oscillate aboutthe connection 224. The resulting movement of the free end 226 of lever220 is insufiicient to cause contact between the same and the projection229 on element 228.

As the engine speed increases, the ow through the valve 236 and thecoolant 234, 244 and 246 is also increased. At a predetermined enginespeed the ow rate is of a suflicient magnitude to cause the ball 242 tobe raised within the interior 240 thereby blocking off the connectionwith conduit 244. At this instant the pressure in the valve interior 238and line 248 will build up and is in turn communicated to the device102. This pressure acts upon one of the diaphragms 108 thus causing theactuator shaft 116 to shift toward the device 102 against the forceexerted by spring 119.

The lever 220 assumes the position shown in Figure 9 at the instant thedevice 102 is energized. The end 226 is thereupon brought into closeproximity to the projection 229 on element 228. Upon movement of theprimary throttle valve to a predetermined position after the device 102is energized, the lost motion gap between the projection 229 and the end226 is closed. Upon further movement of the primary throttle toward theinside open position the secondary throttle valves 208 are opened.

Referring next to the embodiment of Figure 10, a moditied linkagearrangement is shown. The primary barrel is shown at 302 and thesecondary barrel is shown at 304. A primary throttle valve is shown at306 pivotally mounted within barrel 302 and a secondary throttle valveis shown at 308 pivotally mounted within barrel 304. A lever 310 issecured to the primary throttle valve and is manually actuated by meansof the usual throttle linkage.

A lever 320 interconnects one end of the actuator shaft 116 of thepressure responsive device 102 and one end of link 322. The other end oflink 322 is joined to the lever 310.

The secondary throttle valve 308 is secured to an element 328 which hasa projecting portion 376 at one end thereof. An element 324 is rotatablymounted upon the secondary throttle valve shaft at one end thereof andthe other end is connected to the central portion of lever 320 by linkelement 332. The secondary throttle valve is biased toward the closedposition by a spring 330.

In the operation of the embodiment of Figure 10, the movement of theprimary throttle valve causes the lever 320 to oscillate about itsconnection with shaft 116 which causes the element 324 to oscillateabout the secondary throttle shaft by virtue of the connection betweenlever 220 and element 324.

When the engine is operating below a predetermined speed the position ofthe shaft 116 is as shown in Figure 10. Under these conditions theoscillatory movement of element 324 is insufficient to cause Contactbetween the same and the projecting portion 329 on element 328. However,when the device is actuated in the manner previously explained the shaft116 is shifted so as to move the element 324 into closer proximity tothe projecting portion 329. Upon subsequent movement of the primarythrottle beyond a predetermined setting the element 324 will thenContact portion 329 and cause the secondary throttle valve 308 to open.

Referring next to Figure ll, another embodiment is shown wherein thepressure responsive device 102, previously described, is utilized todirectly actuate the secondary throttle valve. As seen in the figure,the actuator shaft 116 of the device 102 is directly connected to anelement 402 which in turn is xed to the secondary throttle shaft.Movement of the shaft 116 will therefore cause the secondary throttlevalve, shown at 424, to oscillate within the secondary barrel, shown at406.

The primary barrel is shown at 408 and has mounted thereon a primarythrottle valve 410. A carn element 412 is secured to the primarythrottle shaft at one end thereof in a convenient location. A suitablemanually actuated throttle linkage is provided at 414, 416, and 418 andis operatively connected to the primary throttle in the usual manner toactuate the same.

A cam follower 420 is suitably mounted upon an actuator rod 422 whichmay be slidably disposed within any convenient structure either on thecarburetor casting itself or at a location remote thereto as desired.The rod and cam follower are biased toward the cam 412 so that the camfollower is maintained in contact with the cam 412 at all time. The rod422 extends within a valve housing 424 through a suitable tubularstructure 426 joined to the housing 424.

The housing 424 is similar to the valve housing previously described inconnection with the previous embodiments and has disposed thereon a ballvalve element designated by numeral 428.

The discharge side of the engine coolant pump 232 is tapped by means ofa conduit 430 which delivers fluid to the interior of housing 424 at apoint directly opposite the tubular structure 226. Another conduit 431extends from the interior of housing 424 to the pressure responsivedevice 102 at one side of the partition 114. Another conduit 432interconnects the space surrounding rod 422 with the device 102 at theother side of the partition 114. A bypass conduit 434 connects theconduit 432 with the intake side of pump 232.

ln the 'operation of-theembodimentof sFigure 'llgthe jprimary throttlelvalve is a'ctuatedink the usual manner by fmeans f* the' manuallyVactuated linkage 4l-4,' -416 'and :418. V`"Whenthe throttle valvef410is in the' closed position, yas fshowninfFigure"ll, lthecam-follower420 causes'the rod *422 to be depressedinto thehousing'M4-thus preventing -theball '428 from rising to they upper portionofthe interior of thetvalve andifromblocking oit/the opening into thetubular structure l426.

When the primary throttle valve `is'movedV to a predeterminedsetting,1therod '422 isrnove'd upwards a sutciently vgreat ldistance topermit the ball423to'block oli` the opening at the Yconnection* withfthetubular structure 426.

'During 'operation' ofV the engine" below a; predetermined speed,theball will'assurn'e"the`position shownin Figure 'll `and the secondarythrottle will-be .maintained closed `.throughout the operating rangeofthe primary throttle 410 "byyir'tue ofltheforce'e'xerted'by spring 119on shaft 116.

During operation of the engine above a predetermined speed and at 'aprimary throttle opening in excess of a 'predeterminedsetting,thc ball428'will be moved by the liquid coolant'passing through 'the valvehousing 424 'thereby causing the passage throughthe tubular structure'rod 422 will'be depressed bythe cam y412 thereby shifting therball 428and opening-the tubular structure 426 and conduit 432 tothe highpressuredischarge side ofpump i232. High pressure coolant-Will therefore beadmitted to vboth working chambers of the device'102 vand the forcesexerted-uponseach of the diaphragms 108 will oppose and cancel eac'hother. 'The spring 119 will thereupon be effective to close theAsecondary throttle valve v404. Thus, the secondary throttle may beopened only when rthe enginespeeds are above apredetermined Value andwhen the primary throttle valve issimultaneously opened to' a positionabove a predetermined setting.

Figure '12 shows another modification of the'invention which employs-adifferent type of quick action control valve. The Valve consists ofahousing v502 which includes two opposed .portions 504 and 5'06 which arejoined' together at matingperipheral flanges 15.08. Aflexiblediaphragm'SlO extends transversely across the interior "of the'housingand-is secured between the. peripheral flanges '508. The central'portion of the diaphragm has secured thereto'apair'ofvalve elements512and l514 which extend perpendicularly'to the plane of the diaphragm. Aspring '516 is interposed'between Ithe housing portion '506 andthediaphragm `51'0 and urges the diaphragm axially in one direction.

A uid conduit 518 interconnects the'high pressure dischargeside ofenginecoolant pump 232 yand a working chamberon one side ofthe diaphragm1510. This cham- 'ber is designated in Figure l2 by the symbol X.Another conduit 520 extends from the working chamber on the other sideofthe diaphragm 510-to the low pressure intake side .of the pump 232.This second working chamber is designated by the symbol CY.

:Valve ports Uare providedat 522 4and 524 substantially in the center ofthe'housingfportions 504 and 506, respectively, and are each connectedto a common conduit v526.

YThe valve `elements`f512 andr514, carried by the diaphragm 510, extendinto close proximity to the lports-522 and 524, respectively. Theconduit 526 is connected at its extreme end to apressure responsiveactuating device 528. A bypass conduit 527 interconnects ,the conduit526 and the valve port 524 in the housing .portion 506.

The device ,'528 consists of apair of Yopposed .housing ,portions 4530and S32 which dene aninter'ior-cavity within which a flexiblediaphragm'534 is transversely disposed.

` Diaphragm 534 may be 'secured about lits periphery vbed tween thematingperipheral'tedges"fthefhousing portions Aprirnary throttle barrelisshown' at536L and atseoondary 'throttlebarrel is shown lat'538.Throttle'valves540 and542 arerotatably mounted withintheiprimary"andsecondary vbarrels respectively. Primary Vthrottle valve 540 may bevactuated by"a"'manually'actuated throttle linkagein the usual manner.The secondary vthrottlevalve 542 is operatively connected' to the'centerfon ldiapl'iravgn 534 by means of linkage elements 54'4`and546.Asp'rin'g 4548 may be interposed betweenthelhousing portion 532 anddiaphragm S34 to bias the secondary'throttle valve into a normallyclosedposition. l

In the operation of the embodiment of 'Figurefll'engine coolant may betapped from the kdiseha'rgedfuthe'pump 232 and conducted into'theworking chamber 'Xthrough conduit S18. During operation of the engine"below a predetermined speed any'coolant which may'pass around L'thevalve element 512into thejport`522will 13e-directed throughtheconduit527`backinto the port y5'2'4andthe'n into the intake side ofthe coolant'pump throughconduit '520. Upon an'increase inthe'enginespeedbeyondthis predetermined limiting speed, the pressurediiferential across the coolant pump^232, which is vvalso appliedacross'the diaphragm'5'10, will cause the diaphragm 510 to'l shift totheright, as viewed in vFigure '12, thus causing the port 524- to becomerestricted while simultaneously opening the port 522. This'shiftingmotionwill cause'a'pressure one side of the diaphragm "534 thuscausingth'esa'me'to in the engine speed to a value below thetpredeter'minedlimit, the diierential pressure ac ross the diaphragm 510 will Ibejinsuiiicient to maintain :the diaphragm '510 and the valve lelementsl"51.2 and )ST4 in 'a'1 shifted position and Ithe spring 516 willbe-eiective toreturn the valve elements to the'neutral position, yasshown in Figure 12.

Figure 13 shows a modified quick action control'valv'e 'which may besubstituted lfor the valve of the embodiment of Figure 1'2. Thismodified valve comprises ahousing 692 which also has two opposedportions604 and '606 joined at mating peripheral ilanges608. A'exiblediaphragm 610 extends across the interior'of lthe housing 602 andcarries atits'center a pair vofiflatvalve elements '612 and '614. vThelfluid conduits which provide communicationbe'tween the pump 232an`d lasecondary throttle 'valve actuating device may be arranged in a mannersimilartothat ofFigur'e r12. 'The-conduits 618 and 620 correspond infunction to`conduits k'5138 and l5'20in Figure 12, respectively.

Valve ports are provided in theho'us'ing portions 1604 and vw'606 at6'22and 624respectively. A spring'638 is interposed'between the diaphragm"61.0 and the housing 'portion A"6106 'and Iis effective 'to Vbias thediaphragm v`a'n'd one'fvalve element'coaxiallygagainst aninwardlydirected extension 636 of the conduit'6246.

lA conduit 626 'is connected to the valve port 622 and vextendstooneside 'of aexible diaphragm within apressure'responsive actuator, notspecifically illustrated. The

other side of the liexible diaphragmof the pressurel responsive actuatoris connected to thelow pressure conduit 620 yby meansl of conduit 634.A'Such a pressure actuatorma-y -include'afhousing andthe liexiblediaphragm therein may divide the-interior'of thehous'ing into apairofworking chambers, each of which are connected to conduits 626 orS34-respectively.

The other side of the exible diaphragm '610.m`ay 'be connected rtoConduit 6 2@ lby means Aof conduit 629. A bypass conduit is providedaty627 which interconnects 'conduit 626 `with port 624.

-In theoperationof the fmodiiied valveof :Figure 13, the pressurediierential `which exists across the pump -232 is impressed uponopposite `sides Vof 1 diaphragm 61'0 through the conduits 618 and 620.During the operation of the engine below a predetermined limiting value,the position of the diaphragm 610 and the valve elements 612 and 614 areshown in Figure 13. Upon a subsequent increase in the engine speed, thecoolant pump pressure becomes sufficiently great to deect the diaphragm610 and its associated valve elements against the force exerted byspring 638 to close the valve port 624 while simultaneously opening port622. The fluid pressure will thereupon increase in the conduit 626, andone side of the exible diaphragm in the pressure responsive actuatordevice. At the same time, the other side of the iiexible diaphragm inthe actuator device is connected to the intake side of the enginecoolant pump. The actuator device is therefore responsive to coolantpressure differential across the pump.

Upon being energized, the actuator device will open the secondarythrottle valve to which it may be linked in the usual manner. Upon asubsequent decrease in pump pressure differential, the spring 638 willurge the valve element 612 against port 622 thus decreasing the pressureacting against the diaphragm of the actuator device.

In all of the preceding embodiments herein disclosed, the actuatingdevice for the secondary stage is responsive only to the pressuredifferential across the engine coolant pump. Therefore the absolutevalue of the pump discharge pressure may be subject to variation withoutaffecting the calibration of the carburetor control mechanism.

While certain preferred embodiments of the invention have beenspecifically disclosed, it is understood that the invention is notlimited thereto as many variations will be readily apparent to thoseskilled in the art, and the invention is to be given its broadestvariation within the terms of the following claims.

l claim:

1. In a liquid coolant internal combustion engine having an intakemanifold and a liquid coolant pump, at least two conduits for supplyinga combustible mixture to said intake manifold, a throttle valve in eachof said conduits, means for actuating one of said valves for controllingthe passage of a portion of said combustible mixture to said manifold,other means for actuating a second valve in another of said conduits tosupply an additional controlled charge of combustible mixture to saidmanifold during the operation of said engine within a predeterminedspeed range, said other means including portions mechanically controlledby said first named means, and means responsive to variation in enginecoolant pump pressure for moving one of said controlled portions to aninoperative position when the engine coolant pressure exceeds apredetermined value during the operation of said engine within anotherpredetermined range of engine speeds.

2. In a multiple stage carburetor for a liquid cooled internalcombustion engine having an engine driven coolant pump, a plurality ofinduction passages, throttle valves in each ofsaid passages, means forcontrolling the operating position of said valves including a portionconnected to one of said valves and another portion connected to anotherof said valves, said means further including a one way mechanicalconnection between said portions which provides for simultaneousmovement of both of said valves during movement of said one valve withina predetermined range of operating positions, and means responsive tovariations in engine coolant pump pressure for adjusting the relativeposition of said portions to render the same ineffective to control theposition of said other valve at engine speeds below a predeterminedlimiting valve.

3. In a liquid cooled internal combustion engine having an enginecoolant pump and an intake manifold, at least two conduits for supplyinga combustible mixture to said intake manifold, a throttle valve in eachof said conduits, means for actuating one of said valves for controllingthe passage of a portion of said combustible mixture to said manifold,other means for actuating a second valve in another of said conduits tosupply an additional controlled charge of combustible mixture to saidmanifold during the operation of said engine within a predeterminedspeed range, said other means including portions mechanically controlledby said rst named means, and means responsive to engine coolant pumppressure for moving said controlled portions to an inoperative positionduring the operation of said engine within another predetermined rangeof engine speeds.

4. In a liquid cooled internal combustion engine having an enginecoolant pump and an intake manifold, at least two conduits for supplyinga combustible mixture to said intake manifold, a throttle valve in eachof said conduits, a tirst linkage element operatively connected to oneof said valves, a second linkage element connected to the other of saidthrottle valves, means for moving said second linkage element into andout of an operative position in response to pressure differential acrosssaid engine coolant pump, said elements being adapted to engage eachother upon movement of said one throttle valve beyond a predeterminedsetting when said second linkage element is in an operative position toactuate the other of said throttle valves and to control the supply ofcombustible mixture to said manifold.

5. In a multiple stage carburetor for a liquid cooled internalcombustion engine having an engine driven coolant pump, a plurality ofinduction passages, throttle valves disposed within each of saidpassages, linkage means for actuating one of said valves, means foractuating the other of said valves having a portion thereof adapted forengagement with a portion of said linkage means during movement of thelatter within a predetermined range of operating positions, and meansfor adjusting the relative positions of said portion of said secondnamed means with respect to said linkage means in response to variationsin coolant pressure differential across said pump.

6. ln a multiple stage carburetor for a liquid cooled internalcombustion engine having an engine driven coolant pump, a plurality ofinduction passages, throttle valves in each of said passages, means forcontrolling the operating position of said valves including a portionconnected to one of said valves and another portion connected to anotherof said valves, said means further including a one way mechanicalconnection between said portions which provides for simultaneousmovement of both of said valves during movement of said one valve withina predetermined range of operating positions, and means responsive topressure differential variations across said engine coolant pump foradjusting the relative position of said portions to render the sameineffective to control the position of said other valve at engine speedsbelow a predetermined limiting value.

7. In a multiple stage carburetor for use with a liquid cooled internalcombustion engine, a primary induction passage, a secondary inductionpassage, primary and secondary valves mounted within said primary andsecondary passages respectively, means for controlling the position ofsaid primary throttle valve, a control element operatively xed to saidsecondary valves, a one way mechanical connection between said elementand said control means for actuating the secondary valve during movementof said primary throttle valve within a predetermined range of operatingpositions, and means responsive to pressure variations between thedischarge and intake sides of said engine coolant pump for renderingsaid secondary valve inoperative during operation of said engine withinanother predetermined range of engine speeds.

8. In a two stage carburetor for an internal combustion engine, aplurality of induction passages, a primary valve in one of saidpassages, a secondary valve in another of said passages, a first linkelement fixed to said primary valve and movable therewith during manualVoperation of said primary Valve, ai-se'cond link member 'fixed tosaldsecondary valve, a third llink member piv- .otally-:connected fnearone end thereof to said second member andoperatively connected to amovable fulcrum lmember at -a `,central portion thereof, said rstVmember-bemg adapted-toengage and actuate said second-'member nearitheother end thereof during movementof the .primary vthrottle through apredetermined frange of engine speeds, .and-meansresponsive to `enginespeed-'for adjusting the-positionV of said 'fulcrum member torender-thesecondary valve inoperative during operation of the eng-ine-wvithinanother-predetermined range lof engine speeds.

`9. Atwo stage carburetor as set forth in claim 8 wherein said engine isvliquid cooled and wherein said 'engine speed 'responsive means includesan actuator device having almovable-actuator shaft, conduit means for=conducting engine coolantto said device thereby providing anenginespeed signalfor energizing the same, `and linkage means connectingsaid fulcrum member to said lactuator shaft.

10. In a two stage carburetor for a liquid cooled internal combustionYengine having an engine driven coolant pump,-a pluralityof inductionpassages, throttle valves -disposed within each `of said passages,linkage means -for manually actuating oneI throttle valve in one of saidpassages, a one Way mechanicalA connection between said fonethrottle=valve and another'throttle valve in another :of said passagesfor actuating said other throttle valve :throughout a predeterminedrange of operating posi- .j ytions for said one Ythrottle valve, saidconnection including'cooperating'linkage elements connected to saidprimary and secondary valvesfrespectively, and means vresponsive toengine coolant pump pressure differential -across said coolant pump forshifting-one of said linkage elements -to a relatively remote positionwith respect to said other linkage element to render said connectioninoperative atfengine speedsbelow a predetermined limiting value.

'11. In aftwo stage carburetor'for a liquid cooled internal combustionengine having an engine driven coolant pump, aplurality of inductionpassages, throttlefvalves disposed yWithin each of said passages,linkage means for manually actuating one throttle valve in one of saidpassages, a one way mechanical connection between said ione-throttlevalve and another throttle valve in another of said passagesforactuating said other throttle valve throughout a predetermined range ofoperating positions for said one throttle valve, said connectionincluding cooperating'linkage elements connected to said primary andsecondary vvalves respectively, means re- `-sponsive to Iengine coolantpump pressure differential `across said coolant pump -for shiftingoneofsaid linkage lelements'to a relatively remote position with respect toysaid other linkage element to render said connection -inoperative atengine speeds below a predetermined limiting value, said pressureresponsive means including an actuator device, a movable actuator shaftvoperatively carried by said device, a mechanical connection betweensaid actuatorshaft and said one linkage element to shift formanuallyactuating one throttle valve in one of said passages, a one waymechanical connection between said one throttle valve and anotherthrottle valve in another of said 'passages for actuating said otherthrottle valve throughout a predetermined range of operating positionsfor said one throttle valve, said connection including cooperatinglinkage elements connected to said primary and secondary valvesrespectively, means responsive to engine coolant pump lpressuredifferential -Iacross-'said `coolant-*pump 'for f'shifting one of said`linkage nelements to Ia 'relatively remoteposition wit-hrespect'toy.said other'linkage element to render said -connect-ion inoperative atengine-speeds`=be1ow la predeterminedflimit- -ing value,wsaidpressureresponsive meansfincluding'an actuator device, fa =movable `actuatorshaft -operatively carried by-said1fdevice, 4Aal'mechanical connectionbetween y"saidfactuatorshaft and said` one" linkage element to `shiftthe"1same, `and conduit structurerinterconnecting-said.devicelfwith saidcoolant pump, said conduit-structureI--in- Icluding a quick-actioncontrol rvalve' interposedltherein Iforcontrolling 'thev transfer of'engine 'coolant 'pump pres- -sure to said'device.

il3. tIinf--a-'multiple stage carburetorfor use with yliquid cooled"internal Acombustion engines 'having an intake ymanifold and an engine'driven' coolant pump, af plurality of passages for supplying a4combustible mixture to said manifold, 'afprimarythrottle valve in-oneof Yfsaid passages, a-"secondary throttle valvei'in another'ofsaidpassages, means =for vrmanually controlling said 'primary throttlevalve, a mechanical 'lost motion fconnectionbetween saidfvalveszincludinglinkage portions having -a'lost `motion Vgap' therebetween;vaf pressure responsive actuating -device,an lactuator ro'd 'forming aport-ion of said device `and connected to another portion of said lostmotion `connection, landconduitmeans for connecting said "device tosaidenginecoolantpump -to provide said device with coolant pumppressure, said actuator 'device being adapted fto move said otherportion-upon 'being energized vwith engine coolant pressure therebyreducing the magnitude of saidf-losttmotion gap.

114. A multiple stage carburetor as setforth in 'claim 113 whereinsaidactuatorfdevicety includes a housing and -a pair of opposed Workingchambers in said housing, and whereinsaid conduitmeans'includesa `fluidcontrol valve housing, -a sphericalv-lve element disposed Within lsaid'housin'g,-a pair of valve portsin said housing and-axiallya'ligne'dw'ith respect thereto, a third valve port located intermediatesaid pair, a'rst conduit interconnecting one of' saidpairofzportsfwiththe 'discharge side of said-pump, a-second conduitconnecting the other-of said pair of tportslwith the-intake side of saidpump, a third conduit connectingsa-id'second conduit to one of saidpairsof -workingfchambers, and 'a fourth conduit connecting said intermediatevalve port to ythe other of said lworking chambers, said spherical Valveelement being adapted to block-the other of said pair of vvalve portsvwhen a pre- .determined vpressure diiferential is reached across said'pump fthereby'fcausing an actuating pressure differential to build-upin said working `c'zharribers to shift ysaid actuatorfrod.

115. Inla multiple stage carburetor for usewith a liquid cooled-internalcombustion engine having an intake manifold and an engine driven coolantpump,a"pluralityof -passages Yfor *supplying 'a lcombustible mixture tosaid manifold, a first-throttle valvein one of said passages, a 4second'throttle valve in another of said passages, la 'linkage for manuallyactuating said rst throttle valve, an engine coolant pressure responsivedevice including a movable actuating member, conduit means for supplyingengine coolant pump pressure to said device to actuate -the same, a lostmotion element fixed to said second throttle valve, anothercooperatinglost motion element rotatably mounted upon a portion of saidsecond throttle valve, a rst link element operatively-connected to saidactuator shaft at one 'end thereof, `said first throttle beingmechanically connected' to vthe other end of said link element, andanother linkconnection between the intermediate portion of said rst linkelement and said other lost motion element.

`16. lIn"combinationwith a multiple stage carburetor for a liquid cooledinternal combustion engine having an engine coolant pump, at least onepair of induction passages, a primary throttle valve in one of saidpassages, a secondary throttle `valve in anotherof said passages;

a pressure responsive actuator device having a movable portion thereofoperatively connected to said secondary throttle to actuate the same, apair of opposed working chambers within said actuator device, fluidconduit structure for delivering coolant pressure from said pump to saidworking chamber, a quick action control valve interposed in said conduitstructure for causing said actuator device to be energized when thecoolant pressure exceeds a predetermined minimum value, and means forrendering said control valve inoperative when the primary throttle isoperated within a predetermined range of positions.

17. The combination as set forth in claim 16 wherein said control valvecomprises a housing, a spherical valve element adjustably disposedwithin said housing, a pair of opposed valve ports in said housing ondiametrically opposite sides of said valve element, an intermediatevalve port in said housing, a rst conduit connecting one of said pair ofports to the discharge side of said pump, a second conduit connectingthe other of said pair of ports to one of said working chambers, a thirdconduit connecting said intermediate port with the other of said workingchambers, a bypass conduit connecting said second conduit to the intakeside of said pump, and wherein said means for rendering said controlvalve inoperative includes a rod slidably disposed within said housingand adapted to control the movement of said valve element, and means formoving said rod into contact with said valve element in response tomovement of said primary throttle valve, said rod thereby preventingmovement of said valve element.

18. In combination with a multiple stage carburetor for use with aliquid cooled internal combustion engine, at least two inductionpassages, a primary throttle in one of said passages, a secondarythrottle valve in another of said passages, a pressure responsiveactuator device having a movable actuator shaft thereof operativelyconnected to said secondary throttle valve, said actuator deviceincluding at least one movable wall element partly defining opposedworking chambers, said actuator shaft being connected to said movableelement, a quick action e control valve, said control valve including aflexible diaphragm partly defining opposed pressure chambers on eitherside thereof, conduit means for connecting said pressure chambers to theintake and discharge sides of said pump, metering ports disposed onopposite sides of said diaphragm, other conduit means for connectingsaid ports to one of said working chamber, and movable valve elementscarried by said flexible diaphragm for selectively restricting saidports in response to pressure differential variations across said pump.

19. The combination as set forth in claim 18 wherein said movable valveelements comprise projections extending at least partially through saidports for variably restricting the same.

20. The combination as set forth in claim 18 wherein said movable valveelements comprise flat valve discs adapted to selectively cover saidports to restrict the same.

2l. A two stage carburetor for use with a liquid cooled internalcombustion engine having a coolant pump and an intake manifold, at leasttwo conduits for supplying a combustible mixture to said intakemanifold, a throttle valve in each of said conduits, linkage means foractuating one of said throttle valves, and means for actuating anotherof said throttle valves in response to coolant pressure differentialacross said coolant pump.

22. In a multiple stage carburetor for a liquid cooled internalcombustion engine having an intake manifold and an engine coolant pump,at least one pair of induction passages for supplying a combustiblemixture to said manifold, throttle valves in each of said passages,linkage means for actuating a first of said throttle valves, a one waymechanical connection between said valves providing for simultaneousmovement of said first and a second of said throttle valves duringmovement of said first throttle valve over a predetermined range ofpositions near the wide open throttle setting, a pressure responsiveactuator device having a pair of opposed working chambers therein, amovable actuator shaft operatively connected to said device, a portionof said one way connection being connected to said actuator shaft,conduit means for connecting said working chambers to either side ofsaid coolant pump, and valve means for regulating the distribution ofcoolant pump pressure through said conduit means so as to selectivelyapply coolant pump discharge pressure to either one or both of saidworking chambers as determined by the magnitude of the engine speed.

23. A two stage carburetor for use with a liquid cooled internalcombustion engine having a coolant pump and an intake manifold, at leasttwo conduits for supplying a combustible mixture to said intakemanifold, a throttle valve in each of said conduits, linkage means foractuating one of said throttle valves, and means for actuating anotherof said throttle valves in response to coolant pressure differentialacross said pump, said last named means including a pressure responsiveactuating device, a fluid passage interconnecting said device with eachside of said coolant pump, and a quick action flow control valveinterposed in said passage for regulating the distribution of enginecoolant pressure in said passage whereby said coolant pressure may beapplied to said device to actuate the same only at engine speeds above apredetermined limiting value.

24. A two stage carburetor as set forth in claim 23 wherein said quickaction control valve includes a valve housing, a flexible diaphragmwithin said housing, valve ports in the wall of said housing on eitherside of said diaphragm, and valve elements carried by said housing forrestricting said ports, said passage including portions connectingopposite sides of said diaphragm to respectively opposite sides of saidpump and other portions connecting at least one of said ports to saidactuating device.

25. A two stage carburetor as set forth in claim 23 wherein said quickaction control valve includes a hollow valve housing, a plurality ofvalve ports in said housing, and a spherical valve element disposedwithin said housing between two of said ports for alternatelyrestricting the same, said passage including portions connecting certainof said ports to respectively opposite sides of said pump and otherportions connecting at least one other port to said actuator device.

26. A two stage carburetor as set forth in claim 23 wherein said linkagemeans include portions comprising a lost motion mechanical connectionbetween said throttle valves.

27. A multiple stage carburetor for a liquid cooled internal combustionengine having an engine driven coolant pump and an intake manifold, saidcarburetor cornprising a primary throttle stage and at least oneauxiliary throttle stage, said stages each including means for supplyinga combustible mixture to said engine manifold, and means for controllingthe operation of said auxiliary stage in response to coolant pressuredifferential across said pump.

28. In an internal combustion engine having an intake manifold, aprimary mixture conduit and a secondary mixture conduit for supplyingsaid manifold with a combustible mixture of fuel and air, a primarythrottle valve mounted in said primary conduit and a secondary throttlevalve mounted in said secondary conduit, linkage means interconnectingsaid primary and secondary throttle valves, said linkage means includinga first linkage element joined to and movable with said primary throttlevalve, a second linkage element joined to and movable with saidsecondary throttle valve, a third linkage element joined at one endthereof to said second linkage element, means for pivoting said thirdlinkage element about a point thereon intermediate its ends, and enginespeed responsive means for shifting said pivoting means to either of twooperating positions, said first linkage element being adapted to contactand rotate said third Alinkage element about said intermediate pointwhen said pivoting .means assumes one of said operating positions as theprimary valve is moved within a predetermined .range `of throttlesettings near the wide open'position thereby opening said secondarythrottle valve, said 'secondary throttle valve remaining in a closedlposition dui'- ing movement of said lprimary throttle valve when saidpivoting lmeans assumes the other of said operating positions.

2'9. The combination as set forth in claim 28 wherein said engine speedresponsive means comprises a pressure responsive actuator havingportions operatively connected to said linkage means, said engine beingprovided with an engine driven engine coolant pump, and conduit meansproviding -communication between said pump and said pressure responsiveactuator, 'said pressure responsive actuator being energized by enginecoolant pressure when the engine speed exceeds a predetermined maximumvalue.

30. In an internal combustion engine having an intake manifold, aprimary mixture conduit and a secondary mixture conduit for supplyingsaid manifold with a combustible mixture of fuel and air, a primarythrottle valve mounted in said primary conduit and a secondary throttlevalve mounted in said secondary conduit, linkage means interconnectingsaid primary and secondary throttle valves, said linkage means includinga first linkage element joined to and movable with said primary valve, asecond linkage element joined to and movable with said secondary valve,an engine responsive actuator including a movable actuator shaft, athird linkage element pivoted at one end thereof to said actuator shaft,an intermediate portion of said third linkage element being joined tosaid rst linkage element, said actuator shaft being adapted to assumeeither of two operative positions, the other end of said third linkageelement being adapted to contact and to rotate said second linkageelement and to open said secondary throttle valve when said actuatorshaft assumes one operating position as the primary throttle valve ismoved within a predetermined range of operating positions near the wideopen setting.

3l. The combination as set forth in claim 30, wherein said engineincludes an engine driven coolant pump and wherein said actuatorincludes a pressure responsive servo mechanism, and conduit structureproviding communica` tion between said engine coolant pump and saidservo mechanism, said servo mechanism being energized upon an increasein engine conduit pump pressure beyond a predetermined value therebyshifting said actuator rod to said one operating position.

32. In an internal combustion engine having an intake manifold, aprimary mixture conduit and a secondary mixture conduit for supplyingsaid manifold with a combustible mixture of fuel and air, a primarythrottle valve mounted in said primary conduit and a secondary throttlevalve mounted in said secondary conduit, linkage means interconnectingsaid primary and secondary throttle valves, said linkage means includinga first linkage element joined to and movable with said primary valve, asecond linkage element joined to and movable with said secondarythrottle valve, an engine speed responsive actuator including a movableactuator shaft, a third linkage element pivoted at one end thereof tosaid actuator shaft, a fourth linkage element pivoted at one end thereofadjacent said second linkage element, the other end of said fourthlinkage element being joined to said third linkage element intermediatethe ends thereof, the other end of said third linkage element beingjoined to said rst linkage element, said second and said fourth linkageelement forming a one-way connection, said actuator shaft being adaptedto assume either of two operative positions and to shift said fourthlinkage element into and out of a position closely adjacent said secondlinkage element, the secondary throttle valve being opened as theprimary throttle valve is moved to a range of posi- 18 tions greaterthan the wide 4open setting, said fourth linkage element being adaptedto contact said second linkage and to open said secondary throttle valvewhen it assumes said position adjacent said second linkage element.

33. The combination as set forth in claim 32 wherein saidy engineincludes an engine driven coolant pump and wherein said 'actuatorincludes -a pressure responsive servo mechanism, and conduit structureproviding communication between said` engine coolant pump and -saidservo mechanism, said servo mechanism being energized upon an increasein engine coolant pump pressure beyond a predetermined value therebyshifting said actuator shaft to one of said operating positions andshifting said fourth linkage element into said position adjacena saidsecond linkage element.

34. In a liquid cooled internal combustion engine having an intakemanifold and` an engine driven coolant pump, iirst and second mixtureconduits for supplying said manifold with a controlled combustiblecharge, a primary throttle valve in the iirst of said conduits, asecondary throttle valve in the second of said conduits, linkage meansfor actuating the first of said valves, pressure responsive means foractuating said secondary throttle valve comprising diaphragm structureand an actuator linkage means interconnectingv said diaphragm structureand said secondary throttle valve, said diaphragm structure defining inpart two opposed working chambers, conduit structure interconnectingsaid coolant pump with at least one working chamber of said pressureresponsive means, and valve means for controlling the distribution ofcoolant pressure to said pressure responsive means, said valve meansincluding a flexible valve diaphragm defining two opposed valvechambers, one of said valve chambers being connected to the highpressure side of said coolant pump and the other of said valve chambersbeing connected to the low pressure side of said coolant pump, said onevalve chamber communicating with one of said working chambers, passagemeans for bypassing fluid from said one valve chamber to said othervalvechamber, and a valve element carried by said valve diaphragm forrestricting said bypass means upon deflection of said valve diaphragm asthe coolant pump pressure differential increases beyond a predeterminedvalue thereby causing a rapid pressure buildup in said one pressurechamber.

35. The combination as set forth in claim 34 wherein said valvediaphragm carries another valve element, said other valve element beingadapted to control the degree of communication of said Working chamberwith said one valve chamber, the degree of communication increasing upondeflection of said valve diaphragm under the inuence of engine coolantpressure differential.

36. In a liquid coolant internal combustion engine having an intakemanifold and an engine driven coolant pump, irst and second mixtureconduits for supplying said manifold with a controlled combustiblecharge, a primary throttle valve in the rst of said conduits, asecondary throttle valve in the second of said conduits, linkage meansfor actuating the first of said throttle valves, pressure responsivemeans for actuating said secondary throttle valve comprising diaphragmstructure and an actuator linkage means interconnecting said diaphragmstructure and said secondary throttle valve, said diaphragm structuredefining in part two opposed working chambers, conduit structureinterconnecting said coolant pump with at least one working chamber ofsaid pressure responsive means, valve means for controlling thedistribution of coolant pressure to said pressure responsive means, saidvalve means comprising a valve chamber, said conduit structure includingseparate portions respectively connecting said valve chamber with thehigh pressure side and the low pressure side of said coolant pump, saidconduit structure including another portion connecting said valvechamber with one of said working chambers, a spherical valve elementdisposed in said valve chamber,

and a bypass passage means communicating with said valve chamber forconducting fluid from the high pressure side to the low pressure side ofsaid pump, said valve means being adapted to restrict said bypasspassage means upon an increase in the pressure differential across saidconduit pump beyond a predetermined value thereby causing a rapidpressure buildup to occur in said one working chamber.

37. The combination as set forth in claim 36 wherein the linkage meansfor said primary throttle valve includes portions for restricting themovement of said spherical valve element upon movement of said primarythrottle valve throughout a range of positions less than a predeterminedsetting thereby preventing a pressure buildup from occurring in said oneworking chamber While said throttle position is in said predeterminedrange.

38. In a liquid cooled internal combustion engine hav- References Citedin the file of this patent UNITED STATES PATENTS 2,282,311 Ericson et alMay 12, 1942 2,376,732 Strebinger May 22, 1945 2,640,472 Bicknell June2, 1953

